1. Field of the Invention
The present invention relates to a method for manufacturing a liquid discharge head for discharging desired liquid by generating a bubble by causing thermal energy to act on the liquid, such a liquid discharge head, a head cartridge using such a liquid discharge head, and a liquid discharging apparatus.
Further, the present invention can be applied to an apparatus such as a printer, a copying machine, a facsimile having a communication system and a word processor having a printer portion for effecting recording with respect to a recording medium such as paper, thread, fibers, cloth, leather, metal, plastic, glass, wood or ceramics and the like, and an industrial recording apparatus combined with various processing devices in a composite manner.
Incidentally, in this specification, the term xe2x80x9crecordingxe2x80x9d means not only that an image such as a character or a figure is applied on a recording medium but also that an image such as a pattern having no meaning is applied to a recording medium.
2. Related Background Art
It is already known to provide an ink jet recording method (so-called bubble jet recording method) in which a change in condition including abrupt volume change (generation of a bubble) is caused in ink by applying thermal energy to the ink, and the ink is discharged from a discharge port by an acting force based on the condition change, thereby forming an image by adhering the discharged ink onto a recording medium. A recording apparatus using such a bubble jet recording method generally includes discharge ports for discharging the ink, ink passages communicated with the discharge ports, and heat generating bodies (electrothermal converting elements) as energy generating means disposed in the ink passages and adapted to discharge the ink, as disclosed in Japanese Patent Publication Nos. 61-59911 and 61-59914.
According to the above-mentioned recording method, a high quality image can be recorded at a high speed with low noise, and, in a head effecting such a recording method, since the discharge ports for discharging the ink can be arranged with high density, a recorded image having high resolution and a color image can easily be obtained by a compact apparatus. Thus, the bubble jet recording method has recently been applied to various office equipment such as printers, copying machines and facsimiles, and has also been applied to industrial systems such as a print apparatus.
On the other hand, in the conventional bubble jet recording methods, since the heat generating member is heated repeatedly while contacting with the ink, deposit of ink may be accumulated on the heat generating member. Further, when liquid to be discharged is apt to be degraded or it is hard to generate an adequate bubble, good liquid discharge may not be achieved by the direct heating bubble formation by means of the heat generating member.
The Applicant has proposed a method for discharging discharge liquid by bubbling the bubbling liquid by thermal energy through a flexible diaphragm isolating the bubbling liquid from the discharge liquid, as disclosed in Japanese Patent Laid-Open No. 55-81172. In this method, a relation between the flexible diaphragm and the bubbling liquid is such that the flexible diaphragm is provided on a part of a nozzle. To the contrary, an arrangement in which a large diaphragm for separating the entire head into an upper portion and a lower portion is disclosed in Japanese Patent Laid-Open No. 59-26270. The large diaphragm is pinched between two plate members defining a liquid passage to prevent liquids in two liquid passages from mixing with each other.
On the other hand, a technique in which the bubbling liquid itself has its own feature and liquid having boiling point lower than that of the discharge liquid is used as the bubbling liquid in consideration of the bubbling feature is disclosed in Japanese Patent Laid-Open No. 5-229122, and a technique in which conductive liquid is used as the bubbling liquid is disclosed in Japanese Patent Laid-Open No. 4-329148.
However, the Inventors found the following problems by investigating the actual manufacturing of the liquid discharge head using the above-mentioned separating diaphragms.
That is to say, since the separation diaphragm is positioned between a substrate having a plurality of heat generating elements and a top plate for forming a common liquid chamber, when the deformable diaphragm is handled as a single piece, the attaching of the diaphragm becomes complicated and the diaphragm may be damaged during its attachment.
Further, it is difficult to adhere the diaphragm to desired positions on the ink passages and heaters of the head and to positively fix an area of the diaphragm other than a movable part thereof, which results in dispersion in discharging ability from part to part. Particularly, when the diaphragm (regarding application filed by the Inventors) is used for obtaining high level liquid discharging while maintaining the effect obtained by the separating ability of the diaphragm, this problem must be solved in a simple manner.
In addition, from another point of view, the Inventors found another new problem when the liquid is discharged on the basis of the bubble formation effected by film boiling using an organic diaphragm and a heat generating member. That is to say, there arises a need (which may occur in practical use) for improving the endurance of the separation diaphragm itself and the ink jet head in consideration of heating factors in the displacement of the diaphragm due to a series of condition changes (generation of bubble, growth of bubble and contraction of bubble).
A first object of the present invention is to provide a method for manufacturing a liquid discharge head, in which the above-mentioned problems can be solved and dispersion in discharging ability from part to part is reduced to improve reliability.
A second object of the present invention is to provide a liquid discharge head which can record a high quality and fine image and in which the above-mentioned problems can be solved and dispersion in discharging ability from part to part is reduced to improve reliability.
The other object of the present invention is to provide associated inventions (described later) such as a method for manufacturing a liquid discharge head, a liquid discharge head, a head cartridge and a liquid discharging apparatus derived by the Inventors in the course of solution of the above problems.
To achieve the above first object, according to the present invention, in a method for manufacturing a liquid discharge head comprising a top plate including a plurality of ink discharge ports for discharging ink droplets, a plurality of first liquid passages for supplying ink in correspondence to the plurality of ink discharge ports and a common liquid chamber for supplying the ink to the first liquid passages, a liquid discharge head substrate obtained by forming second liquid passages arranged adjacent to the first liquid passages and including bubble generating areas disposed adjacent to the first liquid passages on a substrate on which a plurality of heat generating elements for causing the ink discharge port to discharge the ink droplets and including drivers for driving the heat generating elements, and a movable diaphragm for completely separating the first liquid passages and the second liquid passages and displaceable by bubbles generated on the heat generating elements, there is provided a movable diaphragm forming step for providing the movable diaphragm in such a manner that a portion for fixing the movable diaphragm is covered.
According to another aspect of the present invention, in a method for manufacturing a liquid discharge head comprising a top plate including a plurality of ink discharge ports for discharging ink droplets, a plurality of first liquid passages for supplying ink in correspondence to the plurality of ink discharge ports and a common liquid chamber for supplying the ink to the first liquid passages, a liquid discharge head substrate obtained by forming second liquid passages arranged adjacent to the first liquid passages and including bubble generating areas disposed adjacent to the first liquid passages on a substrate on which a plurality of heat generating elements for causing the ink discharge port to discharge the ink droplets and including drivers for driving the heat generating elements, and a movable diaphragm for completely separating the first liquid passages and the second liquid passages and displaceable by bubbles generated on the heat generating elements, there are provided a step for providing the movable diaphragm on a support for forming the movable diaphragm, a step for providing movable diaphragm fixing portions for fixing the movable diaphragm on the movable diaphragm, and a step for removing the support.
According to the above-mentioned liquid discharge head manufacturing method, since the movable diaphragms are integral with the portions for fixing the movable diaphragms, the diaphragms themselves are not handled. Accordingly, a method for manufacturing a liquid discharge head, in which the above-mentioned problems can be solved and dispersion in discharging ability from part to part is reduced to improve reliability can be provided.
To achieve the above second object, according to the present invention, in a liquid discharge head comprising a top plate including a plurality of ink discharge ports for discharging ink droplets, a plurality of first liquid passages for supplying ink in correspondence to the plurality of ink discharge ports and a common liquid chamber for supplying the ink to the first liquid passages, a liquid discharge head substrate obtained by forming second liquid passages arranged adjacent to the first liquid passages and including bubble generating areas disposed adjacent to the first liquid passages on a substrate on which a plurality of heat generating elements for causing the ink discharge port to discharge the ink droplets and including drivers for driving the heat generating elements, and a movable diaphragm for completely separating the first liquid passages and the second liquid passages and displaceable by bubbles generated on the heat generating elements, the movable diaphragm has a frame abutting against the movable diaphragm to support the movable diaphragm.
According to the above-mentioned liquid discharge head, since the frame abutting against the movable diaphragm is provided, during the manufacture, when the movable diaphragm is handled, sufficient rigidity is ensured to prevent damage to the movable diaphragm and assembling alignment can be achieved easily and correctly. Further, since the portions (which become fixed ends (not moved) during the displacement of the movable diaphragm by the frame) of the diaphragm positively act as fixed ends without abutment between the top plate and the substrate, there is no dispersion from part to part and no dispersion depending upon use conditions, thereby stabilizing the discharging feature and recording a highly fine image.
According to another aspect of the present invention, in a liquid discharge head comprising a top plate including a plurality of ink discharge ports for discharging ink droplets, a plurality of first liquid passages for supplying ink in correspondence to the plurality of ink discharge ports and a common liquid chamber for supplying the ink to the first liquid passages, a liquid discharge head substrate obtained by forming second liquid passages arranged adjacent to the first liquid passages and including bubble generating areas disposed adjacent to the first liquid passages on a substrate on which a plurality of heat generating elements for causing the ink discharge port to discharge the ink droplets and including drivers for driving the heat generating elements, and a movable diaphragm for completely separating the first liquid passages and the second liquid passages and displaceable by bubbles generated on the heat generating elements, the top plate, the head substrate and portions of the movable diaphragm abutting against the top plate and the head substrate are formed from material including the same elements.
According to the above-mentioned liquid discharge head, the top plate, the head substrate and portions of the movable diaphragm abutting against the top plate and the head substrate are formed from material including the same elements. Accordingly, when the top plate, the head substrate and the movable diaphragm are assembled, even if the assembling is effected under a high temperature condition, the movable portions of the diaphragm can be prevented from being deviated from the liquid passages. Further, since the heat accumulated in the head during the operation equally acts on the top plate, the head substrate and the abutting portions of the movable diaphragm, the positions of the top plate, the head substrate and the movable diaphragm are not deviated, and excessive force does not act on the abutting portions. Accordingly, since the movable portions and the fixed portions of the movable diaphragm can positively be operated as the movable portions and the fixed portions, a highly fine output image can be obtained.
Further, the present invention provides a head cartridge having the above-mentioned liquid discharge head, and a liquid discharging apparatus having the above-mentioned liquid discharge head.
In addition, as mentioned above, the present invention includes inventions based on recognition of new problems caused when an organic diaphragm is used as the separation diaphragm, and such inventions can be understood from embodiments described later.
Incidentally, in this specification, terms xe2x80x9cupstreamxe2x80x9d and xe2x80x9cdownstreamxe2x80x9d are used with respect to a liquid flowing direction from a liquid supply source through the bubble generating area (or movable member) to the discharge port, or, used as representing the corresponding directions in terms of the structure.